Synchronization is important for telecommunication network performance. Frequency and time (e.g., time-of-day) synchronization is crucial for communication networks, such as those implemented in mobile backhaul architectures. Examples of network synchronization protocols developed to provide this synchronization includes plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), network time protocol (NTP), precision time protocol (PTP), and various GNSS-based synchronization techniques. Of these protocols, PTP is particular advantageous in that it is designed to overcome latency and jitter issues inherent in the other protocols, and in many cases, can provide accuracy in the nanosecond range.
The PTP is defined according to the Institute of Electrical and Electronics Engineers (IEEE) 1588 standard. In general, the PTP standard is a packet timing technology designed to provide precise timing for communication networks. A communication network typically includes a core network having a master node, and one or more boundary nodes and/or slave nodes that are synchronized to the master node. The PTP standard is compatible with most or all Ethernet and Internet protocol (IP) networks. Additionally, the PTP standard is designed to enable a properly designed network to deliver frequency and phase or time with precision rivalling GNSS-based synchronization schemes.
Although PTP-based systems add a small amount of additional traffic to the network load, they have several advantages. First, they work in the data path, and also benefit from the redundancy and resiliency mechanisms of the network, resulting in relatively reliable operation. Additionally, multiple transmission paths reduce redundant clock system costs. They also use a single synchronization session for all base station traffic. The PTP standard supports almost any generic packet-based transport (e.g., IP, MPLS, etc.). The PTP standard also features configurable synchronization packet rates for network conditions to maintain accuracy.
The transmission of the clock information over a packet network eliminates the need for alternative mechanisms, such as GNSS communication or prohibitively expensive oscillators placed at each of the slave nodes. This provides significant cost savings in network equipment as well as in ongoing installation and maintenance. This synchronization solution transmits dedicated timing packets, which flow along the same paths with the data packets, reducing the cost of synchronization and simplifying implementation.